Coating apparatus



,1 R. L. BARTHOLOMEW 2,432,081

COATING APPARATUS File d Sept. 28, 1944 s Sheets-Sheet 1 1947- R. L. BARTHOLOMEW 2.432.081

COATING APPARATUS Filed Sept. 28, 1944 3 Sheets-Sheet 2 ZZY . Dec. 9, 1947.. BARTHOLOMEW 2,432,081

COATING APPARATUS Patented Dec. 9, 1947 I H UNITED STATES PATENT OFFICE COATING APPARATUS Robert L. Bartholomew, Lexington, Mass, assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application September 28, 1944, Serial No. 556,232

8 Claims. 91-17) 1 2 This invention relates to coating apparatus, and nalled in standards 3 mounted upon a frame 4. more particularly to apparatus for coating fila- Two discs 5 and 6 of insulating material are ment coils intended for use as thermionic cathfixed upon said shaft 2 and constitute carrier d means for seizing and holding a filament coil 1 One of the objects of the invention is to provide 5 (see Fig. 3) by its ends, such as a plurality of apparatus for efifecting the coating operation, clamps, herein four such clamps 8 carried by disc thus greatly expediting and facilitating the coat- 5 and four clamps 9 carried by disc 6, said clamps ing operation and very materially reducing the being spaced 90 apart around the periphery of labor cost. said discs. The clamping end of each of the Another object is to provide for the uniform l0 clamps 8 upon disc 5 faces the clamping end of coating of the article to be coated and the unia corresponding clamp 9 upon the disc 6. Means form baking of the coating applied thereto. are provided for rotating said discs, said means Another object is to provide means for conherein illustratively comprising a disc It) provided trolling the viscosity of the coating material to be with a laterally projecting stud H (see Fig. 6) applied to the article. and fixed upon the main shaft I2 of the machine, A further object of the invention is to provide journalled in suitable bearings provided in arms apparatus for coating filament coils. l3 projecting downwardly from the underside of These objects and such other aims and objects said frame 4. A shaft l4, journalled in suitable of the present invention as may hereinafter aphearings in two of said arms l3 and a third arm pear will be readily understood from the follow- I5 extends parallel to said main shaft l2 below ing description, taken in connection with the acthe latter and has fixed thereon a star cam l6 pa y d aw ngs of one embodiment of the provided with four radial slots ll extendingininvention herein presented for illustrative purwardly from its periphery and spaced 90 apart, poses. the edge of said cam l6 between said slots I! be- In the drawings: ing provided with curved surfaces l8 of substan- Fig. 1 is a front elevation of the apparatus intially the same radius as that of a member l9 r0- corporating one illustrative embodiment of the tating with said disc ID, the construction and arinvention, and also shows diagrammatically the rangement being such that as said disc l0 rotates driving motor circuit and the heating circuit of said stud H will'engage the four slots [7 in suct fila t C cession to rotate said shaft 14 through an angle Fig. 2 is an end elevation of the apparatus of 90 for each complete rotation of said main shown in Fig. 1, viewed from the right side of Fig. shaft l2. The member IS on said shaft I 2 is pro- 1; vided with a straight edge portion 20 and an edge Fig. 3 is a top plan view of the apparatus shown portion 2| concentric with saidshaft l2 and which in g. successively engages said surfaces l8 on said star Fig. 4 is a side view of the clamp carrier showcam IE to lock the latter between revolutions ing the four clamps and the four corresponding thereof. Said shaft l4 carries a sprocket wheel contact paths on the outside surface of said clamp 22 which is connected by a sprocket chain 23 with carrier; a sprocket wheel 24 fixed upon one end of the Fig. 5 is a detailed drawing, on an enlarged aforesaid shaft 2 carrying said two discs 5 and 6 scale, of one of the slidably mounted clamps; on which are mounted said clamps 8 and 9. Each Fig. 6 is a detailed drawing of the cam mechpair of opposed clamps 8 and 9 will thus be adanism for periodically rotating the clamp carriers vanced step by step through an angle of 90 for through each complete rotation of said main shaft l2.

Fig. '7 is a detailed drawing of the cam mech- A motor 25 supplied with electrical energy from anism for lifting and lowering the coating fork; any suitable conventional source, such as power Fig. 8 is a detailed drawing of the driving conlines 18 and I9, drives said main shaft l2 through nection between the motor and the speed reduca suitable, conventional speed reduction mechtion mechanism; anism 26 connected to said motor by a belt 21 Fig. 9 is a detail of the cam for stretching the passing over pulleys. 28 and 29 of said motor and filament coil; and said speed reducing mechanism 26 respectively, Fig. 10 is a detailed drawing of the coating and to said shaft l2 by a sprocket chain 30 passfork. ing over a sprocket wheel 3| of said speed re- The illustrative embodiment of the invention ducing mechanism 26 and a sprocket Wheel 32 shown in the drawings comprises a shaft 2, jourfast upon said shaft l2.

Each of the clamps 8 and 3 comprises a fixed jaw 33 and a jaw 34pivoted upon the latter at 35 (see Fig. 3). A leaf spring 36 having one end attached to the fixed jaw 33 and the other in sliding contact with the pivoted jaw 34 tends to keep the jaws of the clamp closed.

Means are provided for opening the clamps 8 and 9 at the proper time to discharge the coated filament coil therefrom. Herein said means illustratively comprises a fixed cam 31 extending beneath each of the discs 5 and 6 concentrically with the latter and in the path traversed by the pivoted jaws of the clamps 8 and 9 in the rotation of said discs (see Figs. 2 and 3). In the rotation of said discs, the pivoted jaws of each pair of clamps 8 and 9 successively engage these cams at the proper time and separate the pivoted jaws from the fixed jaws so as to discharge the filament coil held thereby. After the discharge of the filament coil, the pivoted jaws of the two clamps of each pair remain in engagement with their respective cams 31 until in the further rotation of the said discs 5 and 6 the clamps 8 and 9 arrive at the point where they must pick up another filament coil. The pivoted jaws of the clamps then leave the said cams, and springs 35 close the pivoted jaws upon the fixed jaws to clamp the new filament at its two ends which are in position to be seized, as hereinafter more fully explained, between the open jaws. (See Fig. 3.) The clamps 9 on the disc 6 are immovably anchored in the insulating material of said disc but the clamps 8 on the disc 5 are mounted for sliding movement toward and from the corresponding clamps on said disc 6 in guides 38 which are immovably anchored in the insulating material of the disc 5. A stud 39 (see Fig. 3) attached to the movable clamp projects through a longitudinal slot in the wall of said guides 38 and carries a cam roller 4!] which at the proper time in the revolution of the discs 5 and 6, while the ends of the filament coil are still clamped between the jaws of the clamps 8 and 9, engages a suitably shaped fixed cam 4| carried by an angular standard 4i mounted on the frame 4 of the machine, thus moving the clamp 8 away from its cooperating clamp 9 to stretch the filament. Springs 38 return the clamp 8 to its normal position when, the stretching being completed said cam roller 40 leaves said cam 4i. By loosening nuts 42 and 43 a very fine adjustment of the cam surface 4! can be effected in order to obtain just the desired amount of stretching of the filament coil. In the case of some articles, no stretching may be required, in which case said cam 4| may be adjusted in such a position that it will not contact with said cam roll 40, so that no stretching movement of said slidable clamp will occur. In the case of heavier coil filaments, for example, no stretching is necessary.

A supply of coating material. such as barium monoxide suspended in Nujol, for example, is contained in a suitable container 44. It has been found expedient to regulate the temperature of the coating material and thus control its viscosity, and means are accordingly provided for this purpose. Said means herein conveniently comprises a jacket 45 enclosing the walls of said container. Water or other suitable liquid at the temperature desired may be supplied from a suitable supply, not shown, to said jacket through inlet 46 (see Fig. 3) and may flow out through outlet 41. Said container 44 is carried by a bracket 48 secured upon the upper end of a rod 49 mounted in a fixed sleeve 50 carried by said frame 4.

Means may be provided gently to agitate or stir the coating material in the container 44 to keep the solid matter in suspension, said means herein illustratively comprising a double paddle 5| (see Fig. 2) immersed in the coating material and mounted upon a shaft 52 journalled in an arm 53 of said bracket 48. A sprocket 54, fast upon the upper end of said shaft 52, is conveniently driven by a sprocket 55 (see Fig. 3) rotatably mounted upon the upper end of a rod 56, by a sprocket chain 51, said rod 56 being rotatably mounted in a fixed sleeve 58, mounted upon the frame 4, the lower end of said rod 56 being operatively connected to the main shaft I2 by a right angle bevel gearing 53, 60 (see Fig. l).

The coating material is conveyed to the coil by suitable means, such as a coating fork, herein designated generally by the reference numeral 6|. Herein said coating fork (see Fig. 10) comprises two jaws 6la and 6 lb pivoted by a clamping pivot Me to the end of lever 62. A helical spring 62a bears with its two ends against the jaws Bio and Gib and tends to separate said jaws, while a screw 62b, freely rotatable in jaw Gla and having screw threaded engagement with the jaw Bib, serves to adjust the spacing of said jaws from each other against the tensloned spring 62a. Means are thus provided for varying the capacity of the fork. The opposed inner surfaces 62c and 62d of the two jaws are somewhat concave and near its lower end the inner surface of each jaw is provided with a substantially semicircular recess 62c from which the inner surfaces of said jaws flare outwardly. In the operation of the device more fully described below, said coating fork 6| is first dipped quite deeply into the coating material in the container 44 so that owing to the configuration of space between the jaws of said fork, when said fork is withdrawn from said container, a substantial increment of said material, varying according to the adjustment of the spacing of the two jaws 6ia and Gib will be retained in said fork, filling the space between the semicircular recesses 62c and a portion of the space above said recesses, substantially as indicated by dotted lines in Fig. 10. In order to deposit said increment of coating material upon the filament coil, said fork is lowered until its two jaws embrace the filament between the two semicircular recesses 62c whereupon the coating material in the fork will adhere to and completely immerse the filament coil. The operating mechanism of said coating fork herein illustrated comprises a two-armed lever 62 of which the longer arm carries said coating fork 6i and is fixed upon the upper end of a rod 63 rotatably and slidably mounted in a vertical sleeve 64 mounted upon said machine frame 4. The rod 63 extends for a suflicient distance into the sleeve 64 to be guided thereby in all positions thereof and contacts at its lower end a. rod 63a slidably but non-rotatably mounted in said sleeve 64. Said rod 63a carries a cam roller 65 which rests upon the edge of a butterfly cam 66 fast upon said main shaft [2, and serves to raise and lower said rod 63 and coating fork 6i at the proper intervals. Adjacent its upper end, the above-mentioned rod 56 has fast thereon-a cam 61 which is in operative engagement with a cam sleeve 68 rotatably mounted upon a stud 69 carried by the shorter arm 10 of said two-armed lever 62. A helical spring H surrounding said rod 63 and connected at one :5 end to said rod 63 and at the other end to said fixed sleeve 84 tends to keep said cam sleeve 68 in contact with the edge of said cam 61, so that in the continuous rotation of said main shaft I2, said two cams 66 and 5'! will cooperate to actuate said coating fork 6| at the proper time to convey coating material to the filament coil, said cam 66 raising and loweringsaid coating fork to pick up coating material from said container 44 and discharge it upon the filament coil, and said cam 81 swinging said coating fork back and forth alternately from a position above said container where it can be lowered into said container and raised thereupon by said cam 68, and then into a position above the filament coil where said cam 68 can lower it to deposit its load of coating material upon said filament coil, and then raise it to be moved back over the container 44 by said cam 61.

The shorter arm 10 of said two-armed lever 62 will preferably be adjustably connected to the longer arm of said lever by a clamping screw 12 for adjustment to vary the throw of said lever (see Fig. 3)

In accordance with the present invention, means are provided for heating the filament coil to bake the coating thereon, said means herein conveniently comprising four separate electric contact paths 13 on the outer lateral surface of one of said discs 5 and 6, the disc 5, for example, and each of the clamps 8 carried by said disc is electrically connected to one of said contact paths, which are concentric with said disc 5. A

spring pressed contact brush 14 slidable in an insulating arm 15 mounted upon standards 3 will contact with each of said contact paths 13 in succession as said discs 5 and 5 rotate. The other disc 6 is provided upon its outer lateral surface with a circular contact path 16 concentric therewith and electrically connected with each of the clamps 9 carried by said disc 6 (see Fig. 2). One of the clamps 9 on the disc 6 will always be in contact with the cam 31 under said disc, so that all the clamps on said disc 6 will always be electrically connected to said cam.

The circuit for heating the filament co l may be supplied with energy from any suitable conventional source, such as the power lines 18 and 19 (see Fig. 2). Said circuit comprises a transformer 80, a rheostat 81, an ammeter 8| and two switches, one 82 for the motor circuit and the other 83 for the heating circuit proper. One terminal of said heating circuit is connected to the contact brush 14 and the other to the cam 31 which opens the clamps on disc 6. When in the rotation of discs 5 and 8, one of the contact paths 13 of the disc 5 contacts with the contact brush 14, the circuit for heating the filament coil will be closed through said contact brush 14, contact path 13 on disc 5 with which said brush is in contact, the corresponding clamp 8, holding one end of the filament coil, clamp 9 on disc 6, holding'the other end of said filament coil, contact path 18 on said disc 6, and finally through some other clamp 9 on said disc 6 that is in contact with said cam 31.

A plate 84 is suitably supported at the front of the machine upon a standard 85 mounted upon the frame 4 (see Figs. 2 and 3). Said late is provided with a tongue 86 extending forwardly between the clamping ends of the clamps 8 and 8 when these are in position to seize the filament coil by its ends (see Figs. 3 and 5). In the upper surface of said tongue 86 there will preferably be provided a shallow, transverse slot 81 (see Figs. 3 and 5) to receive each filament coil to be presented to said clampscoil by its ends, said ends will project between the two jaws of said clamps which are open to receive them. Means may be provided, such as a. thin rod 88 carried by the fixed jaw of each clamp and extending across the opening between the two jaws in such a position that when the clamps are in position to seize the ends of a filament coil, said ends will rest upon said rods in position to be clamped between the open jaws.

(See Fig. 5.) A brush 89 may be mounted on the frame in the path of the filament coil, so that said brush 89 meeting said filament coil, as the latter is carried along by said clamps, will remove any excess coating material therefrom.

The apparatus operates as follows, it being understood that the cycle of operation is identical for each pair of clamps 8 and 9, so that a description of the cycle of operation of one pair of said clamps will suffice.

With a pair of clamps 8 and 9 in the position A in Fig. 2, if switches 83 and 82 be closed, the

disc ID will impart a quarter revolution to the star cam l6 and hence to the two discs 5 and 6, thus rotating the pair of clamps from the position A to position B, whereupon said discs 5 and 6 and a pair of clamps come to rest and remain at rest while said disc 18 completes its revolution. During this movement of said pair of clamps the pivoted jaws of said two clamps have been in contact with their respective cams 31, the jaws of said clamps thus remaining open.

In the continued rotation of shaft 2 and said disc ID, the stud II now engages the next slot I l of star cam I6 and rotates it and the discs 5 and 6 through a further 90, said pair of clamps thus arriving at the position C, when they come to rest again. During this further quarter revolution from position B to position C, the pivoted jaws of clamps 8 and 8 leave their cams 31,

thus allowing springs 36 to close the jaws of said clamps 'to seize the ends of the filament coil resting upon the rods 88 between said jaws. In the meantime the cams 68 and 6'! have cooperated, as previously described, to move the coating fork Bl to convey an increment of coating material from the container 44 and deposit it upon the filament coil while it is in the position C. At the start of the next quarter revolution of said discs from position C to position D, the leading end of contact path 13 with which clamp 8 on disc 5 is electrically connected, contacts with the yielding contact brush I4 and the heating current starts to flow through the filament coil held by said clamps 8 and 8 to heat the filament coil and bake the coating thereon, said contact brush remaining in contact with said contact path 13 approximately during the remainder of this quarter revolution, the length of said contact path 13 and the timing being such that the heating of the filament coil will preferably continue for from 5 to 6 seconds. During this quarter revolution of said discs 5 and 6 also, the coated filament coil meets the brush 88 which removes any excess coating material from said filament coil, and the cam roll 48 on the slidable clamp 8 starts along the cam 4| and is thus moved away from clamp 8 and stretching of the filament coil is initiated, and continues approximately to the end of said quarter revolution, when said roll 48 leaves said cam.

41, and the pivoted jaws of clamps 8 and 9 pass onto their cams 31, thus opening said clamps The construc-, tion and arrangement are such that when clamps 8 and 8 move into position to clamp the filament.

and dropping the coated, baked and stretched filament coil into a suitable receptacle 90. During the following two quarter revolutions of said discs and 6 through position A to position B, the pivoted jaws of the two clamps B and 9 remain in contact with their cams 31, as above stated, thus keeping said jaws open to be ready to receive the ends of another filament ready upon the tongue 86 of plate 84, and the cycle above described is repeated.

The present invention marks an important and useful advance in the art. By executing mechanically operations heretofore done by hand it efiects a saving of approximately 90% in labor cost alone; The filament coils are uniformly coated, stretched and baked. Such uniformity of coating, stretching and baking of filament coils was impossible of attainment by hand. Uniformity of coating, however, is important as it makes for a more even and efiicient emission by the filament. Similarly uniform stretching is a great advantage as the filament coils will thus extend in a straight line between their supports in the tube; there will be no sagging to influence the field distribution and cause objectionable capacity effects. Uniformity of baking is also important as it enhances the efiiciency and durability of the filament coil.

Wherever the word plurality occurs in the claims, it is to be understood as meaning two or more.

I am aware that. the present invention can be embodied in other specific forms without departing from the spirit and essential attributes thereof, and I therefore desire the present description to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the aforesaid description to indicate the scope of the invention.

What is claimed is:

1. In coating apparatus, means for applying coating material to an article to be coated, means for seizing an article to be coated, means for actuating said seizing means to seize an article to be coated and to release said article when coated, means for moving said coating applying means relatively to said seizing means to apply coating material to the article seized thereby, and means for rendering said seizing means operative to stretch said article seized thereby.

2. In apparatus for coating filament coils, supply means containing a supply of coating material, conveying means for conveying coating material from said supply means and depositing it upon a filament coil to be coated, actuating means for said conveying means, clamps for seizing said filament coil by its ends, means for actuating said clamps to seize said filament coil to be coated by its ends and to release said filament coil when coated, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, and means for rotating said carrier to bring said clamps into position to seize the ends of said filament coil to be coated and to render said means for actuating said clamps operative to cause said clamps to seize the ends of said filament coil to be coated and to release the coated filament coil.

3. In apparatus for coating filament coils, supply means containing a supply of coating material, conveying means for conveying coating material from said supply means and depositing it upon'a filament coil to be coated, actuating means for said conveying means, separate clamps for seizing said filament coil by its ends, means for actuating said clamps to seizesaid filament coil by its ends and to release said filament coil when coated, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, a contact path on said carrier in the arc of a circle of predetermined length concentric with said carrier, a fixed contact for contacting with said contact path in the rotation of said carrier and electrically connected to one of said clamps, the other clamp and said fixed contact being in circuit with a suitable source of electrical energy, and means for rotating said carrier to bring said two clamps into position to seize the ends of said filament to be coated, and to render said actuating means for said clamps operative to cause said clamps to seize the ends of said filament coil to be coated i and to release the coated filament coil, and to bring said contact path in contact with said fixed contact to close the circuit through the coated filament coil while held between said clamps, to heat said filament coil and bake the coating thereon.

4. In apparatus for coating filament coils, supply means containing a supply of coating material, conveying means for conveying coating material from said supply means and depositing it upon a filament coil to be coated, actuating means for said conveying means, separate clamps movable relatively to each other, means for actuating said clamps to seize said filament coil byits two ends and to release said filament coil when coated, means for moving said clamps relatively to each other, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, and means for rotating said carrier to bring said clamps into position to seize the ends of said filament coil, to render said actuating means of said clamps operative to cause said clamps to seize the ends of said filament coil to be coated and to release the coated filament coil, and to render said means for relatively moving said clamps operative to stretch the filament coil held between them,

5. In apparatus for coating filament coils, supply means containing a'supply of coating material, conveying means for conveying coating material from said supply means and depositing it upon a filament coil to be coated, actuating means for said conveying means, clamps for seizing said filament coil to be coated by its ends, means for actuating said clamps to seize said filament coll by its ends and to release said filament coil when coated, means for presenting a filament coil to be coated to said clamps in position for the latter to seize its ends, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, and means for rotating said carrier to bring said clamps into position to seize the ends of said filament coil to be coated and to render said means for actuating said clamps operative to cause said clamps to seize the ends of said filament coil to be coated and to release the coated filament coil.

6. In apparatus for coating filament coils, supply means containing a supply of coating material, conveying means for conveying coating material from said supply means and depositing it upon a filament coil to be coated, actuating means for said conveying means, clamps for seizing said filament coil by its ends, means for actuating said clamps to seize said filament coil to be coated by its ends and to release said filament coil when coated, means for removing excess coating material from said filament coil, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, and means for rotating said carrier to bring said clamps into position'to seize the ends of said filament coil to be coated, to render said means for actuatin said clamps operative to cause said clamps to seize the ends of said filament coil to be coated and to release the coated filament coil, and to render said means for removing excess coating material from said filament coil operative.

7. In apparatus for coating filament coils, supply means containing a supply of viscous coating material, conveying means for conveying coating material from said supply means and depositing it upon a filament coil to be coated, actuating means for said conveying means, clamps for seizing said filament coil by its ends, means for actuating said clamps to seize said filament coil to be coated by its ends and to release said filament coil when coated, means for regulating the temperature of said coating material to control the viscosity of said coating material, a rotary carrier carrying said clamps and adapted in its rotation to render said means for actuating said clamps operative, and means for rotating said carrier to bring said clamps into position to seize theends of said filament coil to be coated and to render said means for actuating said clamps operative to cause said clamps 30 to seize the ends of said filament coil to be coated and to release the coated filament coil.

8. In an apparatus for coating filament coils, supply means containing a supply of liquid coating material, means for applying coating material to a filament coil, said means comprising a coatin fork having a pair of arms spaced to provide a pocket in which coating material may be carried, means for dipping said arms into said supply of coating material whereby some of said coating material passes into and is retained in said pocket, said last-named means being adapted to move said fork out of said supply and into coating engagement with said filament coil whereby said coating material contained in said pocket is transferred to said coil.

ROBERT L. BARTHOLOMEW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Flaws Nov. 21, 1944 

